The cerebellum provides a tractable model for identifying the genetic and epigenetic factors that influence the morphogenesis of the central nervous system. The mouse is a unique resource in this regard, as over twenty genetic mutant strains have been identified, each of which perturbs a particular aspect of cerebellar development. The most interesting mutations cause disorganization of the cerebellum by disrupting some aspect of cell migration or differentiation. Other mutations cause late-acting progressive degeneration of specific cell types. We are interested in using magnetic resonance microscopy (MRM) to investigate the development of the mouse cerebellum. This technique can be used not only to better describe the normal organization and growth of the cerebellum, but can also provide excellent descriptions of mutant strains. We have recently described a novel mutant strain, meander tail, which harbors a genetic mutation that completely disrupts the anterior cerebellum. This mutation reveals that the cerebellum is organized into rostral and caudal halves, which is a completely unexpected finding. We are interested in developing an accurate three dimensional description of the affected region, so as to more clearly understand the relationship of this gene's action to known functional and anatomical landmarks of the cerebellum. We are also interested in using two other mutant strains that disrupt the normal trilaminar cytoarchitecture of the cerebellum, in order to investigated the correlation between standard histogical techniques and MRM.